Because you are beginning with an empty table, an easy way to populate it is to create a text file containing a row for
each of your animals, then load the contents of the file into the table with a single statement.

You could create a text file pet.txt containing one record per line, with values separated by tabs, and given in the
order in which the columns were listed in the CREATE TABLE statement. For missing values (such as unknown sexes or death
dates for animals that are still living), you can use NULL values. To represent these in your text file, use \N
(backslash, capital-N). For example, the record for Whistler the bird would look like this (where the whitespace between
values is a single tab character):

Whistler Gwen bird \N 1997-12-09 \N
To load the text file pet.txt into the pet table, use this statement:

mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet;
If you created the file on Windows with an editor that uses \r\n as a line terminator, you should use this statement
instead:

mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet
LINES TERMINATED BY '\r\n';
(On an Apple machine running macOS, you would likely want to use LINES TERMINATED BY '\r'.)